AuPt nanoparticles with a Pt-rich surface layer

Bimetallic nanoparticles with controlled size, composition, and structure have gained considerable interest for fuel cell applications. Their catalytic activity is strongly dependent on their surface chemistry. Much effort has been devoted to exploring synthetic methodologies for making a Pt layer over nanoparticles, which are appealing for fuel cell related reactions. However, coating Pt onto metallic particles to create core/shell nanoparticles has been difficult to achieve. Here, we demonstrate a simple wet-chemical synthesis of AuPt bimetallic nanoparticles with a Pt-rich surface. As-synthesized AuPt nanoparticles were characterized by TEM, XRD, and UV-Vis. The Pt-rich surface layer was found by cyclic voltammetry and EDX mapping. Their catalytic activities toward oxygen reduction and methanol oxidation were also compared with pure Au and Pt nanoparticles. The method opens a novel but simple strategy for making core/shell nanoparticles and it is expected to be developed as a general method for producing various nanoparticles with a Pt-rich surface.